The association between prenatal atrioventricular septal defects and chromosomal abnormalities

The rate of trisomy 21 among fetuses identified with an atrioventricular septal defect in the second trimester is high even in those that undergo first trimester combined screening. Some fetuses with a high-risk screening result show a normal karyotype. Therefore, an offer of an invasive procedure to check fetal karyotyping is indicated. Knowledge of these rates may be helpful for parents in the decision making process.